Non-Linearities between Atmospheric Sulphur and Sulphur Emissions

Downing et al. (1995) and others have reported evidence fora non-linearity between atmospheric sulphur and sulphur emissionsin the U.K. Also, there are reports of the effects of the non-linearity being concentrated in regions close to sources. Here we re-analyse the same data in sulphur dioxide versus emission space. Analysis has been carried out at three sites at varying distances from the main U.K. source regions. Annual, seasonal and meteorological categorisations were made to try andclarify observation of any non-linearity. Over long timescales linearity is not excluded. Inter-annual variability is not correlated with emissions. The relation between sulphur dioxideand emissions was found to be least linear for westerly days at asite in southern Scotland. Overall, the extent of non-linearity is not observed to increase with proximity to sources but the relation is least linear for summer days at sites closer to themain source areas.